Pushing the boundaries of radiotherapy-immunotherapy combinations: highlights from the 7 immunorad conference.

Over the last decade, the annual Immunorad Conference, held under the joint auspicies of Gustave Roussy (Villejuif, France) and the Weill Cornell Medical College (New-York, USA) has aimed at exploring the latest advancements in the fields of tumor immunology and radiotherapy-immunotherapy combinations for the treatment of cancer. Gathering medical oncologists, radiation oncologists, physicians and researchers with esteemed expertise in these fields, the Immunorad Conference bridges the gap between preclinical outcomes and clinical opportunities. Thus, it paves a promising way toward optimizing radiotherapy-immunotherapy combinations and, from a broader perspective, improving therapeutic strategies for patients with cancer.

Enhanced tumor control and survival in preclinical models with adoptive cell therapy preceded by low-dose radiotherapy.

Introduction: Effective infiltration of chimeric antigen receptor T (CAR-T) cells into solid tumors is critical for achieving a robust antitumor response and improving therapeutic outcomes. While CAR-T cell therapies have succeeded in hematologic malignancies, their efficacy in solid tumors remains limited due to poor tumor penetration and an immunosuppressive tumor microenvironment. This study aimed to evaluate the potential of low-dose radiotherapy (LDRT) administered before T-cell therapy to enhance the antitumor effect by promoting CAR-T cell infiltration.

Superior antitumor immune response achieved with proton over photon immunoradiotherapy is amplified by the nanoradioenhancer NBTXR3.

Recent findings suggest that immunoradiotherapy (IRT), combining photon radiotherapy (XRT) or proton radiotherapy (PRT) with immune checkpoint blockade, can enhance systemic tumor control. However, the comparative efficacy of XRT and PRT in IRT remains understudied. To address this, we compared outcomes between XRT + αPD1 and PRT + αPD1 in murine αPD1-resistant lung cancer (344SQR).

Inhibition of MER proto-oncogene tyrosine kinase by an antisense oligonucleotide enhances treatment efficacy of immunoradiotherapy.

Background: The combination of radiotherapy and immunotherapy (immunoradiotherapy) has been increasingly used for treating a wide range of cancers. However, some tumors are resistant to immunoradiotherapy. We have previously shown that MER proto-oncogene tyrosine kinase (MerTK) expressed on macrophages mediates resistance to immunoradiotherapy.

Nanoparticle-enhanced proton beam immunoradiotherapy drives immune activation and durable tumor rejection.

The combination of radiation therapy (RT) and immunotherapy has emerged as a promising treatment option in oncology. Historically, x-ray radiation (XRT) has been the most commonly used form of RT. However, proton beam therapy (PBT) is gaining recognition as a viable alternative, as it has been shown to produce similar outcomes to XRT while minimizing off-target effects.

Durable control of metastases in an HLA-A2+ patient with refractory melanoma after low-dose radiotherapy in combination with MAGE-A4 T cell therapy: a case report.

There is no currently approved adoptive cellular therapy for solid tumors. Pre-clinical and clinical studies have demonstrated that low-dose radiotherapy (LDRT) can enhance intratumoral T cell infiltration and efficacy. This case report describes a 71-year-old female patient with rectal mucosal melanoma that had developed metastases to liver, lung, mediastinum, axillary nodes, and brain.

Inhibition of STAT6 with Antisense Oligonucleotides Enhances the Systemic Antitumor Effects of Radiotherapy and Anti-PD-1 in Metastatic Non-Small Cell Lung Cancer.

Diverse factors contribute to the limited clinical response to radiotherapy (RT) and immunotherapy in metastatic non-small cell lung cancer (NSCLC), among which is the ability of these tumors to recruit a retinue of suppressive immune cells-such as M2 tumor-associated macrophages (TAM)-thereby establishing an immunosuppressive tumor microenvironment that contributes to tumor progression and radio resistance. M2 TAMs are activated by the STAT6 signaling pathway. Therefore, we targeted STAT6 using an antisense oligonucleotide (ASO) along with hypofractionated RT (hRT; 3 fractions of 12 Gy each) to primary tumors in three bilateral murine NSCLC models (Lewis lung carcinoma, 344SQ-parental, and anti-PD-1-resistant 344SQ lung adenocarcinomas).

NBTXR3 improves the efficacy of immunoradiotherapy combining nonfucosylated anti-CTLA4 in an anti-PD1 resistant lung cancer model.

The efficacy of immunoradiotherapy consisting of radiation therapy and immune checkpoint blockade relies on effectively promoting the systemic antitumor immune response's activation while simultaneously reducing local factors favoring immune suppression. We previously demonstrated that NBTXR3, a nanoparticle radioenhancer, significantly improved immune responses in a murine anti-PD1-resistant metastatic lung cancer model. We hypothesize that radioactivated-NBTXR3 addition to anti-PD1 and a second-generation anti-CTLA4 could improve treatment effectiveness.

Combining a nanoparticle-mediated immunoradiotherapy with dual blockade of LAG3 and TIGIT improves the treatment efficacy in anti-PD1 resistant lung cancer.

Background: While improvements in immunoradiotherapy have significantly improved outcomes for cancer patients, this treatment approach has nevertheless proven ineffective at controlling the majority of malignancies. One of the mechanisms of resistance to immunoradiotherapy is that immune cells may be suppressed via the myriad of different immune checkpoint receptors. Therefore, simultaneous blockade of multiple immune checkpoint receptors may enhance the treatment efficacy of immunoradiotherapy.

Novel Use of Low-Dose Radiotherapy to Modulate the Tumor Microenvironment of Liver Metastases.

Despite multiple therapeutic approaches, the presence of liver metastases carries a guarded prognosis, urgently necessitating further clinical and scientific research to develop curative interventions. The liver is an immunoprivileged organ that suppresses the effectiveness of immunotherapies in patients with hepatic metastases. Cancer immunotherapies have been successfully bolstered by low-dose radiotherapy (LDRT), which is capable of reprogramming the tumor microenvironment (TME) from an immunosuppressive to an immunostimulatory one.

A multicenter open-label randomized phase II trial of paclitaxel plus EP-100, a novel LHRH receptor-targeted, membrane-disrupting peptide, versus paclitaxel alone for refractory or recurrent ovarian cancer.

Objective: This randomized open-label phase II study evaluated the safety and clinical activity of EP-100 plus weekly paclitaxel in patients with recurrent ovarian cancer expressing positive LHRH receptor.

Methods: In a limited "run-in" dose escalation phase for EP-100, six patients were treated with ascending dose levels (13 mg/m, 20 mg/m, 30 mg/m). In the randomized phase, patients received weekly paclitaxel (80 mg/m intravenously) plus twice weekly EP-100 (30 mg/m intravenously; combination arm) or weekly paclitaxel alone (80 mg/m intravenously; paclitaxel arm).

Enhanced Immunotherapy with LHRH-R Targeted Lytic Peptide in Ovarian Cancer.

Here, we examined the role of EP-100 [luteinizing hormone-releasing hormone (LHRH) ligand joined to a lytic peptide], improving the efficacy of immune checkpoint blockade. LHRH-R-positive murine ovarian cancer cells (ID8, IG10, IF5, and 2C12) were sensitive to EP-100 and were specifically killed at low micromolar levels through LHRH-R. EP-100 increased PD-L1 levels on murine ovarian cancer cells.

GnRH-R-Targeted Lytic Peptide Sensitizes Wild-type Ovarian Cancer to PARP Inhibition.

EP-100 is a synthetic lytic peptide that specifically targets the gonadotropin-releasing hormone receptor on cancer cells. To extend the utility of EP-100, we aimed to identify effective combination therapies with EP-100 for ovarian cancer and explore potential mechanisms of this combination. A series of (MTT assay, immunoblot analysis, reverse-phase protein array, comet assay, and immunofluorescence staining) and experiments were carried out to determine the biological effects of EP-100 alone and in combination with standard-of-care drugs.

Novel LHRH-receptor-targeted cytolytic peptide, EP-100: first-in-human phase I study in patients with advanced LHRH-receptor-expressing solid tumors.

Purpose: To conduct a phase I study determining the safety, pharmacokinetics and preliminary efficacy of EP-100, a novel anticancer drug consisting of natural luteinizing-hormone-releasing hormone (LHRH) ligand linked to a cationic membrane-disrupting peptide.

Methods: Patients with advanced, solid tumors, positive for LHRH receptor by immunohistochemistry (IHC), received EP-100 weekly or twice weekly for 3 of 4 weeks in a 28 day cycle. A modified Fibonacci 3 + 3 dose-escalation schema was used.

Molecular MRI for sensitive and specific detection of lung metastases.

Early and specific detection of metastatic cancer cells in the lung (the most common organ targeted by metastases) could significantly improve cancer treatment outcomes. However, the most widespread lung imaging methods use ionizing radiation and have low sensitivity and/or low specificity for cancer cells. Here we address this problem with an imaging method to detect submillimeter-sized metastases with molecular specificity.

iDQC anisotropy map imaging for tumor tissue characterization in vivo.

Intermolecular double quantum coherences (iDQCs), signals that result from simultaneous transitions of two or more separated spins, are known to produce images that are highly sensitive to subvoxel structure, particularly local anisotropy. Here we demonstrate how iDQCs signal can be used to efficiently detect the anisotropy created in breast tumor tissues and prostate tumor tissues by targeted (LHRH-conjugated) superparamagnetic nanoparticles (SPIONs), thereby distinguishing the necrotic area from the surrounding tumor tissue.

Pharmacokinetics and pharmacodynamics of Phor21-betaCG(ala), a lytic peptide conjugate.

Phor21-betaCG(ala), a 36-amino acid peptide comprised of a lytic peptide (Phor21) conjugated to a modified 15-amino acid segment of the beta-chain of chorionic gonadotropin (betaCG(ala)), selectively kills cancer cells that over-express luteinizing hormone/chorionic gonadotropin (LH/CG) receptors by disrupting cellular membrane structure. These studies were designed to further characterize its in-vitro inhibition and in-vivo destruction of prostate cancer cells, biostability and pharmacokinetics to determine its pharmacokinetic and pharmacodynamic profile. Inhibitory effects of Phor21-betaCG(ala) were tested in PC-3 and Caco-2 cells as well as in nude mice bearing PC-3 cells transfected with the luciferase gene (PC-3.

Glutaric acid as a spacer facilitates improved intracellular uptake of LHRH-SPION into human breast cancer cells.

Superparamagnetic iron oxide nanoparticles (SPIONs) bound directly to luteinizing hormone releasing hormone (LHRH) have shown high efficiency for intracellular uptake to breast cancer cells, MDA-MB-435S.luc. We demonstrate in this communication that inclusion of a small spacer molecule such as glutaric acid (Glu) in between SPION and LHRH increases further receptor mediated intracellular uptake.

Effective treatment of human breast tumor in a mouse xenograft model with herpes simplex virus type 1 specifying the NV1020 genomic deletion and the gBsyn3 syncytial mutation enabling high viral replication and spread in breast cancer cells.

A new oncolytic and fusogenic herpes simplex virus type 1 (HSV-1) was constructed on the basis of the wildtype HSV-1(F) strain. To provide for safety and tumor selectivity, the virus carried a large deletion including one of the two alpha4, gamma(1)34.5, alpha0 genes and the latency-associated transcript region.

Conjugates of lytic peptides and LHRH or betaCG target and cause necrosis of prostate cancers and metastases.

In a series of in vivo and in vitro experiments, it was shown that membrane disrupting lytic peptides (Hecate, Phor14, or Phor21) conjugated to a 15 amino acid segment of the beta chain of CG or to LHRH were able to target and destroy hormone dependent and independent human prostate cancer xenografts in nude mice. In vitro sensitivity of the cells to the drugs was directly related to LH/CG receptor expression, and pretreatment in vitro or in vivo with estrogens or FSH to enhance LH/CG receptor expression capacity and increased sensitivity to the drugs. Administration of unconjugated Hecate and LHRH was ineffective.

Destruction of breast cancers and their metastases by lytic peptide conjugates in vitro and in vivo.

In a series of in vivo and in vitro experiments, the concept has been established that breast cancer cells that express LH/CG or LHRH receptors can be targeted and destroyed by constructs consisting of a lytic peptide moiety and a 15-amino acid segment of the beta-chain of CG or by an LHRH lytic peptide conjugate. Data obtained in vitro established the validity of this concept, showed the specificities of the Hecate-betaCG, and Phor14 and Phor21-betaCG conjugates in killing cells that express functional LH/CG receptors and proved that the LH/CG receptor capacity is directly related to the compound's specificity. In in vivo experiments, Hecate-betaCG, Phor14-betaCG, and Phor21-betaCG(ala) each caused highly significant reductions of tumor volume and tumor burden in nude mice bearing breast cancer xenografts; Hecate and Phor21 alone or conjugated with non-specific peptides were not effective.

LHRH-conjugated magnetic iron oxide nanoparticles for detection of breast cancer metastases.

Targeted delivery of superparamagnetic iron oxide nanoparticles (SPIONs) could facilitate their accumulation in metastatic cancer cells in peripheral tissues, lymph nodes and bones and enhance the sensitivity of magnetic resonance imaging (MRI). The specificities of luteinizing hormone releasing hormone (LHRH) and luteinizing hormone/chorionic gonadotropin (LH/CG)- bound SPIONs were tested in human breast cancer cells in vitro and were found to be dependent on the receptor expression of the target cells, the time of incubation and showed saturation kinetics. In incubations with MDA-MB-435S.

Sub-cellular accumulation of magnetic nanoparticles in breast tumors and metastases.

In this study, the sub-cellular accumulation of superparamagnetic iron oxide nanoparticles (SPIONs) in breast tumors and peripheral organs were investigated. MNPs were conjugated with luteinizing hormone releasing hormone (LHRH), whose receptors are expressed by most types of breast cancer cells. After the nanoparticles were injected into female nude mice bearing MDA-MB-435S.

Targeting breast and prostate cancers through their hormone receptors.

A targeted treatment that effectively destroys human breast, prostate, ovarian, and testicular cancer cells that express luteinizing hormone/chorionic gonadotropin (LH/CG) receptors has been developed. The treatment consists of a conjugate of a membrane-disrupting lytic peptide (Hecate, Phor14, or Phor21) and a 15-amino acid segment of the beta chain of CG. Because these conjugates act primarily by destroying cell membranes, their effects are independent of cell proliferation.

Membrane disrupting lytic peptides for cancer treatments.

Membrane disrupting lytic peptides are abundant in nature and serve insects, invertebrates, vertebrates and humans as defense molecules. Initially, these peptides attracted attention as antimicrobial agents; later, the sensitivity of tumor cells to lytic peptides was discovered. In the last decade intensive research has been conducted to determine how lytic peptides lyse bacteria and tumor cells.